Question

What was the purpose of the first Earth Day event on April 22, 1970?

Answer 1

First proposed by peace activist John McConnell at a UNESCO Conference in San Francisco in 1969. The First Earth Day was organized for March 21, 1970 by the United Nations.
One month later, New York Senator Gaylord Nelson, founded a Earth Day "teach in" under the direction of Dennis Hayes. The first "teach in" took place on April 22, 1970. The idea was to bring awareness to the population of the responsibility for each of us to share in the stewardship of the Earth and it's resources.

Explanation:

Ironically the first and second Earth Days were celebrated in the same year, 1970.
First proposed by peace activist John McConnell at a UNESCO Conference in San Francisco in 1969. The First Earth Day was organized for March 21, 1970 by the United Nations.
One month later, New York Senator Gaylord Nelson, founded a Earth Day "teach in" under the direction of Dennis Hayes. The first "teach in" took place on April 22, 1970. The idea was to bring awareness to the population of the responsibility for each of us to share in the stewardship of the Earth and it's resources.
In 1990 the event became an annual international celebration of the Earth and now includes more than 140 countries around the world.